docs: def global_mean(field):
      """Calculates the latitude weighted global mean of a field
      with latitude dependence.
  
      :param Field field: input field
      :raises: :exc:`ValueError` if input field has no latitude axis
      :return: latitude weighted global mean of the field
      :rtype: float
  
      :Example:
  
          initial global mean temperature of EBM model::
  
              >>> import climlab
              >>> model = climlab.EBM()
              >>> climlab.global_mean(model.Ts)
              Field(11.997968598413685)
  
      """
      try:
          lat = field.domain.lat.points
      except:
          raise ValueError('No latitude axis in input field.')
      try:
          #  Field is 2D latitude / longitude
          lon = field.domain.lon.points
          return _global_mean_latlon(field.squeeze())
      except:
          #  Field is 1D latitude only (zonal average)
          lat_radians = np.deg2rad(lat)
          return _global_mean(field.squeeze(), lat_radians)